I'm not sure what boat training you're talking about. I just did my sea boating license last year in Croatia, and it was all in a room, just like the exam.

When I was doing my original boating license, again the practical part on water was about 20 minutes (starting / stopping and saving somebody from water)

I had much more road practice in my road driving license included, and there wasn't anything unnecessary taught there, I still use 90% of the things taught then when I am driving.